Automatic transmission control



R. E. LA'SSITER AUTOMATIC TRANSMISSIONICONTROL 2 Sheets-Sheet 1 Fild Dec. 10, 19:54

lIlIllIlIIIII/IIIIIIIIII I n I I INVENi'OR. I fills/z 62 awn ATTORNEYS.

Oct, 18, 1938. R. E. LAssrrER 2,133,543 v.

AUTOMATIC TRANSMISSION CONTROL- Fil ed Dec. 10, 1954 2 Sheets-Sheet 2 v INVENTOR- fiuslz 6. fiassz'ier ATTORNEY?- UNITED STATES PATENT OFFICE 2.13am su'rous'rrc massnss'ron con'raor. am a. Lassiter, Detroit, Mich, a-ignor a, The

Monopower Corporation, Detroit, main, a corporation of Application December 10. 1934, Serial No. 756.903

80laiml.

.lfhisinvention relates to automatic transmissions for. controllingly varying the torque and speed ratios between driving and driven elements.

and is particularly concerned with controlling the power transmitted by explosion engines as they are used in the driving of motor vehicles as well as in other services, in accordance with torque and speed demands and conditions. The transmissions of this character most widely used in motor cars up until the present day have been arranged for direct manual control by the driver, usually through the agency of a simple shifting lever. Numerous designs and constructions have been suggested providing for automatic shifting, in aneifort to eliminate the necessity for performing this operation manually, as well as to enable removal of the shifting lever from its usually obstructing position in the driver's compartment. Qther-benents sought to be attained by automatic ontrol are smoother operation, and elimination of the danger of stripping gears through inexpert operation. All of those mentioned also constitute oblects of this invention.

1 Numerous difnculties have been encountered in the variousattempts to reduce such automatic transmissions to practicable and marketable form, however. In addition to the problem of cost, thatof providing automatic control sufllciently responsive to all conditions has been a troublesome obstacle. A primary object of this invention, therefore, is to provide improved and extremely flexible controlling means for such an 1 automatic transmission.which controllingmeans is not only of simple and inexpensive construction in itself, but involves no complication of the trans- I mission to which it is applied, is usable in connection with transmissions of various if not of virtually any desired construction, and provides simple means whereby the shifting of transmission ratios may be governed responsivelynot only to the speed but also to the torque demand or load upon the engine.

Still another object is the arrangement of the controlling means in such manner that while shifting of the effective driving ratio may normally be governed in response only to speed changes of the vehicle or driven shaft, an undue torque demand results in changing the operation of the governing means, under the influence of my improved automatic controlling system, in a manner adapted to establish and/or maintain a higher torque drive during the period of increased torque demand. t

Still further I aim to provide in conjunction with my'invention simple means for preventing (Cl. ll-336.5)

unduly rapid or fluttering operation of the controlling mechanism in event of erratic operation of the engine.

Still another object is the provision of simple means for controlling the operation of an automatic transmission in accordance with torque demands upon the prime mover under the direct regulation of pressure variances created in the prime mover by variation of such torque demand.

Other objects and advantages will be apparent from thefollowing description whereinreference is made to the accompanying drawings illustrating preferred embodiments of my invention, and wherein similar reference numerals designate similar parts throughout the several views.

In the drawings:

Figure 1 is a somewhat diagrammatic vertical sectional elevation of the transmission of a motor car, incorporating a preferred embodiment of my controlling means and fragmentarily showing the engine and other appurtenant portions of the vehicle;

Figure 2 is a detail cross section taken substantially on the line 2-4 of Figure 1 and looking in the direction of the arrows; and

Figures 3, 4 and 5 are enlargeddiagrammatic sectional views of the controlling valve mechanism, showing the same in different positions assumed thereby in operation.

Referring now to the drawings, reference character l0 designates generally a gasoline or other internal combustion engine, the intake manifold of which is indicated at It. Through a main clutch H the engine drives a shaft l5 to which is directly connected an automatic transmission, housed in a casing i8 and supported by a forward casing bell iia whlch'also serves as a clutch housing and is bolted as at I1 to the rear wall of the crank case of the engine.

Although the torque converting mechanism of the transmission forms no part of my present invention, and in fact conforms to disclosure of patent application Serial No. 706,232, filed January 11, 1934, by Robert B. Aspinwall, such mechanism will nevertheless be briefly described herein in order that the operation of my improved controlling mechanism may be understood:

The transmission shaft 20 is piloted and rotatable at its forward end, as in roller bearing 22, in driving sleeve portion 23 forming a continuationof drive shaft is. These parts are journaled in the front wall of the transmission casing as in anti-friction bearing 24. Main gear 25 carried by drive sleeve 23 meshes with main countershaft 5t gear 25. Through these gears are drivable, the low, intermediate and reverse countershaft gears 21-25-25 respectively. The low speed and reverse gears 21-25 are rotatable as a unit with main gear 25, to which they are connected by interfltted splines as at 5| through the countershaft sleeve 55, with which said gears are integrally formed. Intermediate gear 25 is drivable through an over-running clutch arranged in its hub, and connected to main gear 25 through integral sleeve 55.

The transmission shaft 25 carries slidably splined upon its rear extremity a gear and overrunning clutch assembly generally designated 55, movable longitudinally along the shaft by means of shifter fork 55, manually operable through shifter rail 51 which may be controlled as through the agency of a Bowden wire 55 from a dash control assembly 55. By this means the gear portion 55 may be moved to engage either the low speed gear 21, with which it is shown meshed in the drawings, or coupled through reverse idler to counter-shaft reverse gear 25 by sliding it to an extreme rearward position, at which time the lockout clutch teeth 55 render the overrunning clutch 55 in the hub of the gear ineifective by engaging the cooperating clutch teeth 55 carried by the driven coupling member 55. The gear and overrunning clutch assembly 55 may also be moved to an intermediate neutral position in which the gear 55 meshes with neither of the gears 21-.

Intermediate counter-shaft gear 25 meshes with a second speed gear 5I carried by the transmission shaft and normally rimning free thereon but adapted to be coupled to said shaft through the agency of a fluid operable multiple disc friction clutch 52. The driven web 55 of this clutch is shown as formed integrally with the transmission shaft and as also constituting the driven member of another similar clutch 55 arranged upon the opposite side thereof and adapted when engaged to directly couple the drive sleeve 25 to the transmission shaft 25, and thus establish direct drive, since the driven coupling 55 is directly keyed to the transmission shaft as by splined connections 55. The pressure plates 51-55 of clutches 52-55 constitute the pistons of fluid pressure applying motors independently operable through oil channels drilled in the transmission shaft; channels 5I-52-55 providing the fluid connection for actuating the clutch 52, while fluid passages 55-55-55 similarly conduct the motivating fluid to and from the operating motor of clutch 55.

It will be seen that when both clutches 52-55 are disengaged, a low speed drive is effective through the counter-shaft to gear 55, and thence to the driven coupling, if said gear is meshed with the low speed gear 21. (as it is shown in the drawings). Similarly, with both clutches disengaged. neutral or reverse may be established by moving assembly 55 to either intermediate or rearmost position. Upon the engagement of clutch 52, however, which normally occurs in proper sequence after the vehicle attains a desired speed in low gear, driving connection to the transmission shaft and so the rear wheels through coupling 55 is established through gears 25-5I and clutch 52, over-running clutch 55 looking in this direction. The intermediate drive thus established being of higher speed than the low speed drive imparted to gear 55, overrunning clutch l4 releases and overruns that gear.

Up n engagement of clutch 55 to establish d1- rect drive, overrunning clutch 55 will of course release in similar fashion to allow the transmission shaft to overrun in event clutch 52 is not instantly released.

Fluid for moving clutch actuating pistons 51-55 is supplied to ports "-55 through a manifold element 15 containing annular manifold channels "-12 encircling and in sealed en agement at their edges with shaft-'25, and covering respectively the orbits of 'supply'passages "-54. The fluid is fed to the manifold connecting passages 15-15 through slip couplings 15-11 providing connection with valve outlet ports -15-15. The controlled delivery of motivating fluid to these ports is effected through control valve 15, the delivery 55 of which is movable from the blanked position in which it is shown in Figura l and 3 into registry with either of said ports 15, 15 or with relief port 55, in progressive stepped movements to the right, as viewed in the drawings. Movement of the valve is induced by fluid pressure under the control of a pilot valve 55 whose delivery chamber 55 when in the extreme left position shown, registers with port 5I to provide communication through the central passage 52 of the valve to chamber 55 of control valve 15, wherein the reaction of the fluid pressure against the flxed wall 55 maintains the control valve in the lefth'and position in which it is shown in Figures 1 and 3.

The fluid will be seen tobe delivered to valve 55 through oil channel I55, to which it is supplied under pressure from pump means presently to be described. Simultaneously with its delivery to chamber 55 through central passage 52 and the feeding and outlet ports 55-55 thereof respectively, fluid passes through chamber 51 of valve 55 to the delivery passage 55 of valve 15, to which it is conducted through communicating ports 55 connecting the valve bodies, chamber III of valve 15, and central passage I55 of that valve, to and from which the fluid is delivered through inlet and outlet openings l52-I55 formed in the valve body within chambers Ill and 55 respectively. It will be seen that when both valves 15-55 are in the left-most position, as shown in Figure 3, the pressure channels to both clutches 52-55 are connected to atmosphere by the chamber I of valve 15, which provides connection between the ports 15-15 leading to the clutches, and a relief port 55, open to the atmosphere within the casing. Upon movement of the pilot valve 55 one step to the right, however, to register its discharge chamber 55 with port I55, the pressure fluid passing through such port' and the communicating passages, as best shown, in Figure 4, is delivered to the space designated I55 between the fixed wall I51 and head I55 of a slidable collar I55 fltted on a stem 5 secured to and projecting axially from the end of valve 15. The collar may be seen to be slidable with relation to both the valve stem and casing, but the length of the collar is such that delivery of fluid to chamber I55 in the manner described. in moving-the collar to the right, forces its end against a head III carried by the valve stem H5. Movement of the collar in this manner thus also moves the entire valve 15 to the right a like distance.

Fluid is at the same time delivered from valve inlet I55 to connecting. port 55 through valve chamber 51, whence it passes to the discharge passage 55 of valve 15 through the central passage I55, and is by the discharge chamber delivered to port 15 communicating through the channels previously described with the actuating motor of a,1ss,o4s intermediate drive clutch n. The consequent engagement of this clutch establishes intermediate speed drive, as above described. Such drive is maintained until the speed of the governing mechanism (presently to be described) is sufficient to move the pilot valve 88 anotherstep to the right and register its discharge chamber 98 with another port II2, as best shown in Figure 5. Upon such registry fluid is delivered through this port to the chamber II3 provided between the fixed abutment II4, which limits the extreme movement of the valve 15, blocking the heads I88-I I I, and by pressure against the head I II moves the control valve to the right to the extreme position shown in Figure 5, at which time the pressure fluid is delivered from outlet chamber 88 of that valve to the direct drive clutch 55, through port 19 with which chamber 88 is then registered, and the communicating passages previously described.

It will be noted that when the valves are in position to energize the intermediate speed clutch, as shown in Figure 4, direct drive clutch 55 is deenergized by connection of its supply port 19 with relief port 85 through valve chamber I84, while when in the direct drive position shown in Figure 5, clutch 52 is deenergized by connection through port 18 with the atmosphere via the space designated I I5 left unoccupied by the movement of the valve to the right.

Relief ports as H6, H1, and H8, open to the atmosphere within the casing, are provided for venting the chambers I86--I I3.

The pilot valve 88 will be seen to at no time oppose delivery of pressure fluid to .-the delivery chamber 88 of control valve 15, but to function merely to move the latter valve to the several described positions. In the left-most position of the control valve, in which it is shown in Figures 1 and 3, both clutches 52-55 are deenergized, and the only effective drive may be ad th ou ea 48, if the latter is in mesh with either of the gears 21-4 I, while progressive movement of the control valves to the right establishes the second and direct drives successively in the manner described.

The pumping mechanism comprises a gear pump, the gears of which are designated I58I5I drivable through gears I52-I53, the former carried by the driven shaft. The pump draws oil from the bottom of the casing through inlet pipe I54, and delivers it through outlet passage I55 to the supply channel I56 of the valving mechanism previously described. Constant pressure fluid supply is maintained by a relief valve I51.

Driven by the propeller shaft through a connection with one of the pumping gears (I5I),

furnished by the shaft I59 of the latter, is a centrifugal governor assembly I68 arranged to upon increase of speed depress the governor shaft I61. The governor shaft rests upon a valve operating lever I62, which is formed as a bell crank adapted to directly move the pilot valve 88, as clearly shown in the drawings. The valve and actuating lever and governor shaft are yieldably held in raised position, and the flyweights I63 urged inwardly, by a compression spring I64 trapped upon the stem of the valve and urging it to the left as viewed in the drawings. The flyweights acting through their supporting linkage are of course so balanced against the centrifugal force developed by the flyweights when rotated at the speeds induced by operation of the vehicle throughout its intended speed range, as to move the valve to the second and third positions previously described upon attainment of predetermined rates of speed by the vehicle, provided such valve movement is not prevented or reversed .by the suction torque control mechanism now to be described:

Carried upon the top of the casing, in the shown construction, is a vacuum cylinder I18 within which is vertically reciprocable a piston I12 yieldably urged upwardly by a spring I13 encircling the piston rod I14, which projects downwardly and into the transmission casing. The upward force of the spring is opposed by reduction of pressure below the piston, which is designed to be effected in response to a pressure drop in the intake manifold of the engine, to whichthe chamber beneath the piston is connected as by tubes I16-I11. The chamberbeneath the piston also houses spring I13, and is of course virtually sealed to the stem I14, as by closely fitting the slidable bearing support to the rod at the lower extremity of the housing, (at I18). The tube I16 communicates with the chamber beneath the piston through a port I19, and a tank I15 is interposed in the vacuum line between the vacuum cylinder and intake manifold to act as a delaying agent relative to predetermined flow capacity of the conduits adapted to prevent sudden and quickly changing pressure variances from directly affecting the piston, thereby preventing erratic reciprocation of the rod I14. The spring I13 is so balanced with respect to the normal vacuum or pressure drop induced in the intake manifold of the engine as to elevate the piston only when the pressure drops lower than is normal.

Carried by the lower extremity of rod I14 within the transmission casing is a blocking arm I88. Such arm normally moves in a path in vertical alignment with the path of the end of lever I62, so that upon elevation of rod I14 and consequently of arm I88, induced by vacuum drop, the downward movement of valve actuating lever I62, and consequent shifting of the pilot valve to a higher speed position (farther to the right), are blocked or opposed by the added resistance of spring I13, which upon occasion may also be effective, as will be apparent, to return the valve to a lower speed position. The arm I88 may be swingable away from its normal blocking position concurrently with movement of manually shiftable element 35 away from forward toward neutral or reverse position. The movement of the arm out of normal blocking position is effected through the shifter rail 31, which swings the arm through the agency of va vertical actuating rod I82 carried by and upstanding from the rail and slidably fitted in the slotted end of an angular arm I83 formed integrally with blocking arm I88. These parts are so disposed, as best shown in Figure 2, that movement of the shifter rail to slide the unit 35 away from forward drive position to neutral or reverse results in swinging the blocking arm out of the path of the valve actuating lever, preventing any interfer-,

and blocking arm I88 are elevated, and accordingly would interfere with the pilot valve operating arm I62 while gear 48 was in neutral were it not for the fact that the blocking arm is moved clear of the path of the operating lever, as above stated, concurrently with movement of gear 40 to the neutral position. It will be seen therefore that under such conditions, with the slidable gear in neutral position, the governor 'will cause engagement of clutches 52-55 upon the vehicle reaching the predetermined speeds. and that the engine may accordingly be started, as is sometimes convenient or necessary, by the momentum of the vehicle when it is rolling freely,

or by towing the same, whereas arm I80, except for the swingability thereof by the pin I82, would prevent or delay the engagement of clutches 52-55 under such conditions.

While it will be apparent that the illustrated embodiments of my invention herein disclosed are well calculated to adequately fulfill the objects and advantages of my invention, it is to be understood that the invention is susceptible to variation, modification and change within the spirit and scope of the subjoined claims.

What I claim is:

v 1. In combination with an internal combustion engine having an intake manifold, an element drivable by said engine, an automatic transmission interposed between the engine and drivable element for changing the relative torque ratio therebetween, regulatable means for varying the torque ratio through said transmission, speedresponsive governor means for automatically controlling said regulating means, pressureresponsive means connected to said intake manifold including a pressure chamber portion and a movable element therewithin, mechanical connection between said movable element and the governor means, said element being movable to oppose a decrease of torque ratio and destroy the full efiectiveness of the governor means upon a rise of pressure within the manifold, and delaying means preventing instantaneous reversal of movement of said movable element comprising a chambered member of excess capacity arranged between the manifold and pressure chamber and connected to both.

2. In combination with an internal combustion engine having a portion within which pressure variances occur in response to variations of relative torque demand thereupon, and variable ratio torque converting means for changing the effective torque output thereof, a shiftable element for controlling the ratio of the torque converting means, automatic means including a speed reresponsive centrifugal governor for moving said shiftable element in opposite directions, and a pressure-operable element normally opposing movement of said shiftable element only in its travel in a direction toward a position of reduced relative torque ratio, said element being movable by the relative pressure within said portion of the engine, when it is sufllciently reduced, to a. position of non-interference with automatic shifting of said shiftable element under the infiuence of said automatic means.

3. In combination with a prime mover having a portion within which pressure variances occur in response to changes of relative torque demand thereupon, an automatic transmission for varying the effective torque output of the prime mover, including ratio changing means and a shiftable element for controlling the same, automatic means including a speed-responsive centrifugal governor for moving said shiftable element in opposite directions and tending to decrease the relative torque ratio responsively to increasing speeds, biasing means including a spring-pressed blocking arm normally *opposing movement of said element toward the reduced torque ratio position when positive pressures exist within said portion of the prime mover, but allowing independent movement of said element in the opposite direction toward higher torque ratio positioning, and oflsetting means including a pressure-operable motor connected to said portion bithe prime mover and to said blocking arm to move the latter against spring pressure and reduce the effectiveness of said biasing means with the suflicient reduction of pressure within said portion of the prime mover.

4. In combination with a prime mover having a portion within which pressure variances occur in response to changes of relative torque demand thereupon, an automatic transmission incorporating a reverse drive and forward drives of variant ratios, a shiftable element for changing the eilectiveness of said ratios, speed-responsive governor means for moving said shiftable element, apressure operable element for blocking movement of said shiftable element responsively variances occur in response to changes of relative torque demand thereupon, an automatic transmission incorporating a reverse drive and forward drives of variant ratios, a shiftable element for changing the eflectiveness of said ratios, a centrifugal governor for moving said shiftable element in response to speed variations, pressureoperable means connected to said portion of the engine within which pressure variances occur and'having a portion biased to oppose movement of the shiftable element in the direction in which movement thereof is induced by the governor under increasing speeds, said means being movable out of blocking position by decrease of pressure in said portion of the engine, and by discontinuance of forward drive.

6. In combination with a prime mover having a portion within which pressure variances occur responsively to changing relative power demands thereupon, an automatic transmission including torque converting means of variable ratio, means including a shiftable element for controlling the torque converting means, yieldable means for automatically shifting said element, pressure-operable means connected to said portion of the prime mover and including a blocking member movable in and longitudinally of the path of movement of said shiftable element and arranged to yieldably oppose movement of said shiftable element in one direction only, and at such time to cooperate with said yieldable means to modify its controlling effect upon said torque converting means.

7. In combination with a prime mover having a portion within which pressure variances occur responsively to changing relative power demands thereupon, an automatic transmission including torque converting means, means including a shiftable element for changing the efiective ratio of the torque converting means, actuating means for yieldably urging said element in eitherof two directions including speed responsive governor means, and counter-actuating means opposing the effort of said governor means, pressure-operable means connected to said portion of the prime mover and including a blocking member movable in and longitudinally of the path of movement of. said shiftable element and arranged to yieldably oppose movement of said element in one direction only, said blocking member being movable by decrease of pressure in said portion of the prime mover in the direction of movement of the shiftable memher when influenced by increasing speed, to thereby free said member for movement in either direction.

' 8. In combination with a prime mover having a. portion within which pressure variances occur in response to changing relative power demands thereupon, an automatic transmission connected to said prime mover including torque converting means of variable ratio for controlling the torque output oi'said motor, driving and driven mem-' bers, an element shiftable town; the effective torque ratio of the transmission, speed responsive rection in which the shiftable element is urged by speed increase, said spring means normally urgingsaid arm against said element to resist similar movement of the latter, and pressureoperable means connected to said portion of the prime mover within which pressure variances occur, and to said blocking arm, and arranged to move the arm against the effort of the spring means and free the shiftable element for move- .ment in either direction, upon a sufficient decrease of pressure in said portion of the prime mover.

RUSH E. LASSITER. 

